A lottery drawing or the like is generally done by first extracting at least one ball from a batch of balls mixed in the same receptacle, each having a value different from that of the other balls, and second receiving each extracted ball on a track or in at least one conduit; the ball comes to a stop at the end of the track or conduit, or against the last previous ball received.
To enable the operator and spectators to read the results of the drawing easily, each ball is generally marked several times by a sign corresponding to the value represented, such as a number. These signs are distributed about the ball in such a manner that regardless of the position in which the ball comes to a stop, a directly readable sign is always available facing the operator.
Considering the sums of money generally involved, the balls must be perfectly balanced, must adhere to very close tolerances in weight, and must be marked in a very legible manner. During the drawing, the balls are tumbled before being drawn, for example by rotating the receptacle containing them. This subjects the balls and their markings to wear by abrasion as they roll on one another and on the inside wall of the receptacle.
At present, the balls are made from spheres on the surface of which the distinctive signs, in particular numbers, are marked superficially by means of stencils. Given the spherical form of the surface on which the sign is placed and given that a plurality of distinctive signs must be marked on the surface of the same ball, and that for esthetics reasons it is also necessary for the distinctive signs to be regularly distributed about the ball, the difficulties presented by this operation of marking of the balls will readily be appreciated.
To facilitate the operation of marking and permit mass production of the basic ball, a method is known (French Patent 2.577.429), according to which a core with a spherical envelope is made that regardless of the sign to be placed on it has identical sites at the locations of the marking signs. A pellet is placed in each of these sites, with the pellet having a shape complementary to that of the site and having been superficially marked beforehand with the proper sign. This method makes it possible to make the marking before the pellet is put in place and hence while the pellet is still flat, which is clearly simpler than marking directly on the curved surface of the ball. However, the fact remains that this marking, like the one on the ball itself, remains superficial and is not resistant to the aforementioned abrasion over the long term.
Another method is also known (French Patents 2.577.429 and 2.141.231), in which the pellets are made of transparent material. The sign is placed on the back of the pellet or at the bottom of the site or on an intermediate plate. Though the sign is well protected against abrasion, the outer surface of the pellet is still subject to abrasion and will rapidly become opaque, in which case the sign becomes illegible. Moreover, the differences in material between the pellets and the core make for irregular rolling and rebounding as well as irregular wear of the balls.
For the mark to remain visible for a long time, methods for deep marking, instead of the above superficial marking, are also known. In one such method (U.S. Pat. No. 3,364,607), the ball is made in three principal parts, a spherical core and two hemispherical half shells enveloping the core. For the marking per se, an insert is molded separately, which includes a concave base that has the sign to be placed, right side out, located in relief on its upper face. This insert is then fastened tightly between the envelope and the core, before the sign, in relief, is engraved by force in the envelope, which is done by pressing the envelope against the core. Finally, the top of the reliefs of the sign are exposed by finish-grinding of the outer surface of the ball, and the sign remains substantially legible until the entire envelope has worn away.
Although this method gives good results in terms of resistance to abrasion, it is difficult to use when using a sign made of the same material as the envelope, which would make its engagement in the envelope uncertain. Moreover, even if the sign is engraved from the inside face of the envelope, it deforms, which makes it less legible and creates irregularities in density that are incompatible with the regularity of rolling and rebounding that gambling balls must exhibit. Further, the two half-shells create an additional irregularity at their junction.
In another method for deep marking (French Patent 2.050.827), when the ball is molded, voids representing the signs are left in the wall. In the course of a second injection operation, these voids are filled with a certain quantity of synthetic material of a color different from that of which the ball is made, to make the sign show up. Although this method gives good results in terms of resistance to abrasion, to be performed it requires as many ball molds as there are separate signs to be applied, and moreover, for injecting the signs on top of the balls, precise positioning of the ball is difficult to obtain.